"It is impossible, if no more than one opinion is uttered, to

"It is impossible, if no more than one opinion is uttered, to make choice of the best: a man is forced then to follow whatever advice may have been given him; but if opposite speeches are delivered, then choice can be exercised. In like manner pure gold is not recognized by itself; but when we test it along with baser ore, we perceive which is the better."--Herodotus on freedom of discussion. From the series Great Ideas of Western Man.